A delivery truck driver was crushed early Monday by a bundle of rebar being unloaded from his truck, officials at the scene said.
An ambulance rushed the severely injured worker to a local hospital, where he died, according to a spokesman for Turner/Devcon, the construction firm building the stadium.
"We are deeply saddened to confirm that the driver has passed away as a result of his injuries," spokesman Jonathan Harvey said.
The man was an employee of Gerdau Ameristeel's Napa Reinforcing Steel facility, a subcontractor on Levi Stadium, said Gerdau Ameristeel spokeswoman Kimberly M. Selph.
In a statement, the 49ers said their "sincerest thoughts and prayers are with the family, friends and co-workers affected by this tragedy."
The stadium is in Santa Clara, about 40 miles south of Candlestick Park, which it is replacing. Construction is slated to be finished in July, and crews have been working in high gear to meet that deadline. Officials say the accelerated work plan involves a highly coordinated scheme to maximize efficiency and avoid delays.
Construction firm investigators also were on-scene Monday, to see what could have been done to prevent what is now the second deadly accident at the site.
An elevator mechanic, 63-year-old Donald White, was killed at the stadium in June when he was struck by a counterweight while working in a shaft.
White worked as an elevator mechanic for more than 40 years and was employed by Schindler Elevator Corp.
The $1.2 billion stadium project is expected to open its doors just in time to host the 50th Super Bowl, in 2015, in the heart of the Silicon Valley. The airy, open stadium would have the largest lower bowl in the league, ensuring the 68,500 fans are close to the action.
The construction costs are being paid by $800 million in seat and luxury box sales, along with a 20-year, $220 million naming rights agreement with Levi Strauss and Co. announced in May.